Iran's all-powerful supreme leader on Thursday rejected a US offer to negotiate one-on-one on Tehran's nuclear ambitions, ruling out such contacts so long as Washington keeps up its threats against the Islamic republic.

"I am not a diplomat but a revolutionary and I speak frankly," Ayatollah Ali Khamenei told air force commanders. "You (Americans) are pointing the gun at Iran and say either negotiate or we will shoot."

"Some rejoice at the offer of negotiations, (but) negotiations will not solve anything," he said, adding that those in Iran who prefer to risk "American domination" by negotiating with Washington would be "dealt with."

Khamenei has the final say on all key issues in Iran, including sensitive nuclear activities and foreign policy.

His stance appeared to contradict that of Foreign Minister Ali Akbar Salehi who said on Monday that he detected signs the US was rethinking its approach towards Tehran.

Khamenei said, "Iran will not accept to negotiate with he who threatens us with pressure," in reference to a list sanctions adopted by Washington to coerce Iran into curbing its nuclear program.

"The offer of talks is meaningful when the other side shows goodwill," he said.

The remarks come at a time when Tehran and six world powers are preparing to resume stalled talks over Iran's nuclear program in the Kazakh city of Almaty on February 26.

"Does imposing, in your own words, crippling sanctions show goodwill or hostility?" Khamenei said, responding to a new offer of bilateral talks proposed by US Vice President Joe Biden last week.

AFP